The present invention relates to a method for manufacturing a membrane electrode assembly (MEA) for a fuel cell, the MEA containing a layer system of an anode electrode, a cathode electrode and a membrane arranged therebetween.
German Utility Model Patent DE 298 11 922 U1 describes a fuel cell having two outer plates and an electrode/solid electrolyte system formed by electrodes and at least one solid electrolyte located between the electrodes, the outer plates projecting over the electrode- and solid electrolyte system with their edge, and the space formed between the outer plates and surrounding this system being filled with a seal formed of a curable sealing compound. Upon curing, the plastic material forms a frame between the outer plates which seals the interior space of the fuel cells from the outside in a gas-tight manner and which additionally fixes electrode/solid electrolyte system as well.
Known from German Patent Application DE 195 42 475 A1 is a PEM fuel cell having distribution plates which are made of an elastic, plastically deformable material and feature integrated gas or liquid channels. In order for the individual gas or liquid spaces to be sealed from each other, provision is made for integrated elevations in the distribution plates. These elevations are made by an embossing process, the embossing die used featuring corresponding elevations for forming the gas or liquid channels as well as corresponding depressions for forming the sealing arrangement.
Polymer electrolyte membrane fuel cells are composed of an arrangement of a plurality of membrane electrode assemblies that are separated by bipolar plates, a so-called stack, the membrane electrode assemblies (MEA), in turn, being composed of two catalytically active electrodes for electrochemically converting the chemical substances and of an ion-conducting electrolyte between the electrodes for charge transfer. The bipolar plates are used for separating the gas spaces and for electrically linking the individual cells. The functional requirements of a composite configuration of that kind are a gas- and liquid-tight seal between the fuel cell stacks, preventing, on one hand, loss of working gases and, on the other hand, evaporation of water and the resulting drying out of the polymer electrolyte membrane. The sealing of the gas space between the two bipolar plates and the membrane electrode assemblies is difficult since the upper layers of the MEA have a porous design because of their function.
During the assembly of fuel cells, the polymer electrolyte membranes tend to be contaminated by dust or the like because of the direct handling. Dust but also changing air humidity during storage influence the current-generating capacity of the fuel cell.